1. Field of the Invention
The present invention relates to a work platform for a sawing machine and more particularly, to a worktable that is extendible in two steps.
2. Description of the Related Art
FIGS. 1–3 show a platform assembly for attaching to an object constructed according to U.S. Pat. No. 6,619,348. The platform assembly 1 comprises a base 2, two beams 3, two rails 4, a first end board 5, a second end board 5′, four blocks 6, a plate 7, and two stops 8. The beams 3 are disposed in parallel on the top wall of the base 2, each having a groove 3a formed therein. The two rails 4 are respectively slidably received in the groove 3a of each beam 3. The first and second end boards 5 and 5′ respectively secured to the ends of the rails 4. The four blocks 6 are secured to the bottom wall of the plate 7 and coupled to the rails 4 to selectively engage with either of the end boards 5 and 5′. The plate 7 is slidably supported on the rails 4. The two stops 8 are disposed on the base 2 between the beams 3. FIG. 2 is a schematic drawing showing the plate 7 moved leftwards. When two of the four blocks 6 are moved with the plate 7 leftwards after contacting the first end board 5, the two rails 4 will be moved together with the plate 7, and the movement of the plate 7 will be stopped upon engagement of the second end board 5′ with the stops 8. At this time, the plate 7 is at the left side of the base 2 as shown in FIG. 3.
According to the aforesaid design, the plate 7 is slidable relative to the base 2 to extend the work area of the object supporting the platform assembly 1. In actual practice, this design of platform assembly 1 is still not satisfactory in function. As shown in FIG. 2, when the plate 7 is stopped after having been extended out, the plate 7 protrudes over the base 2 at a distance. At this time, the plate 7 is partially coupled to and supported in the groove 3a of each beam 3 through the rails 4. When the plate 7 carries a heavy object, the rails 4 may be forced to curve or break due to excessive long arm of force.
Further, because the plate 7 and the two rails 4 are not lockable, they slide freely within a range. More particularly after the plate 7 has been extended out, it may be pushed back accidentally. This unexpected retraction of the plate 7 makes trouble in the processing work.
Therefore, it is desirable to provide a worktable that eliminates the aforesaid drawbacks.